The services are being touted as a good way to use this information to attract and retain customers, and something banks could easily copy.

Mint Software Inc. is planning to roll out a tool that will automatically scan its 800,000 users' accounts for potentially bogus charges, and last week Wesabe Inc. announced a service that scans for recurring charges on its users' bank accounts. (Wesabe executives say the company has hundreds of thousands of users, but will not give a more specific figure.)

Aaron Patzer, Mint's founder and chief executive, said the idea for the new product came after his company heard of a scam involving Adele Services of Melville, New York, a bogus merchant that was making 25-cent charges to millions of consumer accounts.

The Mountain View, Calif., company decided to make it a standard feature for its site as early as April. Patzer chided banks for not offering similar products.

"You'd think that banks could move this out to their users, but they don't," he said. "They just don't move fast enough and they just don't have the technology in place - at least, I've never seen it - to send out those kind of very specific alerts just to those users who are affected."

George Tubin, a senior research director at TowerGroup Inc. in Needham, Mass., an independent research firm owned by MasterCard Inc., said aggregation sites have access to huge amounts of consumer data, and their owners are wise to develop ways to use it.

However, banks have excellent fraud-monitoring technology and are probably just as capable as Mint, if not more so, of finding bogus charges, Tubin said. "If somebody is a customer of a large institution, this type of fraud detection will be happening for them," he said, though "not every bank has it."

Marc Hedlund, Wesabe's co-founder and chief executive, said that many people have authorized recurring charges long ago and have since forgotten they are paying them every month. Wesabe's Cutback Tool finds such charges, helping people eliminate unnecessary expenses. The San Francisco company aggregates data from accounts at multiple financial companies.

Tubin said such a service is an excellent example of finding ways to analyze financial data to benefit customers.

Wesabe's service "is brilliant in its simplicity," he said. "When you think about it, it's such a straightforward thing that a bank can do that you wonder why they don't."

One reason banks might not be following suit is that some recurring fees are charged by banks themselves; when one of Wesabe's employees tested the service, it spotted a regular charge from her bank that she quickly cut.

(Of course, recurring fees come from a variety of sources, and not all are unwanted. "The No. 1 most popular cutback so far is Netflix," the DVD subscription service, according to Hedlund. And the suggested cut that "people most often reject is also Netflix.")

Ron Shevlin, a senior analyst at Aite Group LLC in Boston, said that "banks need to be interested in" such services, but "they have not figured out how to calculate the ROI and monetize this."

Customers find tools like Wesabe's to be extremely useful because it takes the tedium out of managing their finances, he said. "Money is really, really important to us, but we really, really don't like managing it."

Even if these tools prove popular on Wesabe and Mint, people would still be willing to go to their banks for the same data, Shevlin said. "The Wesabes and Mints, despite their adoption numbers, we're still not talking anywhere near the vast majority of consumers yet. So there's plenty of opportunity for banks and credit card companies to kind of get back into this game, but if they're going to sit there and go, 'Where's the ROI?' on every one of those investments, they're never going to move on doing any of this stuff."

Hedlund said Wesabe's Cutback Tool could be adapted to look for fraudulent transactions, and this could help persuade prospective users who are nervous about using aggregation sites because they fear giving a third party access to their bank data.

"There is some opportunity to help people get through that if they felt this is not just a bank tool, this is a fraud detection tool," Hedlund said.

He said the service is particularly helpful in this economy. "A lot of people are coming to this tool with a particular need. They've been laid off or they're worried about being laid off."

The Cutback Tool is designed to let users decide for themselves what to cut, he said, and makes no assumptions about what would be best for users. "We've come up with a set of suggestions that are absolutely perfect for some people and horrible for other people," he said. It suggests any recurring expenses - even loan and insurance payments, which most people don't cut - to highlight how much money is spent on each over time.

Patzer agreed that by adding fraud detection features, aggregators could hold more appeal to people who have been wary of using such sites. "It takes away some of that apprehension," he said.